1. Field of the Invention
The present invention relates to an animal fiber to which shrink proofing and pilling resistance are given, and a method for preparation thereof. More specifically, the present invention relates to an animal fiber to which shrink proofing and pilling resistance are given without impairing a superior water repellent property that animal fibers originally possess and a method for preparation thereof.
2. Description of the Prior Art
Animal fiber is peculiar natural fiber having specific hand-feeling texture depending on sheep breeds, revealing bio-degradability, having various excellent properties such as hygroscopicity, moisture-releasing property, heat retaining property, flame retardancy and dyeing property, and further, water-repellency. It is special fiber which has appropriate fiber strength and elongation permissible for wear and higher abrasion resistance, also from the standpoint of fiber mechanical properties, and has been esteemed for long time. However, felting property in aqueous washing and pilling property in wear derived from a cuticle tissue structure of animal fiber are undesirable natures as apparel wear. Therefore, studies for improving the surface have been long effected mainly on shrink proofing, and pilling resistant work has also been conducted along with the studies. However, any of animal fiber obtained like this is an improving method sacrificing the water repellency which is an inherent nature of animal fiber. A water repellent membrane of animal fiber is an organization for exerting an influence on hygroscopicity and moisture releasing property and for controlling heat transfer accompanied by adsorption and desorption of water, and exerts an influence on heat retaining property and comfortability. In other words, the conventional shrink proofing product can prevent shrink by aqueous washing, but lacks in heat retaining property and comfortability.
As a conventional typical shrink proofing work, there is a shrink proofing method using a chlorine agent, and specifically, what is called chlorine-Hercosett shrink proofing method in which a cuticle tissue of animal fiber is hydrophilizated, the tissue is made soft or removed to impart shrink proofing property, and further, the cuticle tissue is coated with a polyamide epichlorohydrin resin (Hercosett resin, manufactured by Dick Herculess) for enhancing the resistance to aqueous washing. Currently, this method is spread around the world, and recognized provisionally as a complete method as a shrink proofing method of wool.
However, from the stand point of environmental conservation spread currently around the world, a shrink proofing work using a chlorine agent and chlorine-containing resin has caused a problem of the discharging amount of an Adsorbable Organic Halides (AOX), and a novel shrink proofing method of animal fiber using no chlorine agent is being studied presently. However, a satisfactory method replacing the chlorine-Hercosett shrink proofing method has not been developed yet.
Japanese Patent Kokai No. 126997/1975 discloses a method in which dyeing property and shrink proofing of wool and pilling resistance of a wool-synthetic fiber blended product are improved without deteriorating hand-feeling and fiber strength of wool according to a procedure in which wool sliver is impregnated with an aqueous solution of acids or acidic salts and drained by squeezing rolls, and is placed in a sealed chamber previously filled with an ozone-containing gas having an ozone concentration of 35.5 mL/L, and further, treated at 50° C. for 10 minutes while feeding a new ozone-containing gas. However, this method carries out only oxidation into a cystine crosslinked bond (—S—S—) which performs main role of wool shrink proofing, and no reduction treatment is conducted. In the case of wool, a —S—S-bond is not cleaved until this reduction treatment and this cleavage gives satisfactory shrink proofing to wool, therefore, sufficient shrink proofing and pilling resistance can not be obtained by the disclosed method. Further, the above-mentioned methods is conducted in a sealed system since the treatment should be conducted in an ozone gas atmosphere, and exposure is effected with the aid of molecular movement of an ozone gas, therefore, when the amount of wool treating is increased, unevenness of an ozone gas exposure can not be avoided, and this directly produces a unevenness treatment and uniform wool shrink proofing and dyeing are not obtained. At the same time, in the above-mentioned method, the productivity is low due to the sealed system treatment, and when an ozone gas leaks directly out of the treating apparatus, deterioration in working environment and environmental charge are large, and industrialization is difficult.
Japanese Patent Kokai No. 142759/1980 discloses a method and an apparatus in which fiber is treated with an ozone-steam mixed material. In this method, worsted knitted fabric made of keratinous animal fiber is suspended on a belt conveyor circulating in a special treatment apparatus equipped with an exhaust apparatus, steam is introduced in this apparatus to increase the temperature to 79° C., a fan is started to introduce an ozone-air mixed gas (ozone introduction amount: 3.4 g/minute) and this mixed gas retained in the apparatus for 8.25 minutes to impart shrink proofing. Also in this method, only ozone oxidation is conducted, and no reduction treatment is effected. Therefore, the imparted shrink proofing is not satisfactory, and further, an ozone gas tends to leak due to the defective construction of apparatus, inviting deterioration in working environment.
Japanese Patent Kokai No. 19961/1991 discloses a method of shrink proofing of animal fiber using ozone as an oxidizer. It describes that an ozone gas is passed through a glass filter to give fine bubbles, in a water bath, and this bubbles are allowed to contact animal fiber. But bubbles generated through a glass filter or the like are too large to render ozone gas bubbles to reach fine portions in a fiber assembly, and treat only the surface of the fiber assembly. It is well known from experience that when a wool product containing about 90% of shrink-proofed wool fiber and about 10% of un-shrink-proofed wool fiber in mixture is washed in water, it is shrunk in the same extent as a un-shrink-proofed wool product, whereas, in the above-mentioned method, an unevenness exposure on wool by an ozone gas makes a unevenness treatment, and sufficient shrink proofing is not obtained due to this unevenness.
Japanese Patent Kokai No. 72762/1998 discloses a method in which fiber is immersed in the form of tow, thread, fabric, knit fabric and the like into a water-dissolved ozone prepared by dispersing in water an ozone-containing gas composed of ozone and oxygen or air in the form of bubbles having a diameter of 0.08 mm or less. It describes a method in which an ozone-containing gas is introduced in water to form bubbles, this bubbles are broken by allowing it to collide against small walls in a line mixer when it passes through the line mixer, to give fine bubbles having a diameter of 0.08 mm or less showing enhanced solubility in water, for obtaining ozone dissolved in water having high concentration. This is merely a method for treating rayon and other fiber using ozone in dissolved in water.